For adults with minor head injury: GCS 13 to 15 after witnessed loss of consciousness, amnesia or confusion. Any one finding means the rule calls for CT.
What you enter
GCS <15 at 2 hours after injury
Suspected open or depressed skull fracture
Any sign of basal skull fracture (haemotympanum, raccoon eyes, CSF otorrhoea or rhinorrhoea, Battle's sign)
Vomiting ≥2 episodes
Age ≥65
Amnesia before impact ≥30 minutes
Dangerous mechanism (pedestrian struck by a motor vehicle, occupant ejected from a motor vehicle, fall from ≥3 feet or 5 stairs)
FORMULACT if any high-risk finding (GCS <15 at 2 h, open or depressed skull fracture, basal skull fracture sign, vomiting ≥2, age ≥65) or any medium-risk finding (amnesia before impact ≥30 min, dangerous mechanism)
SourceStiell IG et al. The Canadian CT Head Rule for patients with minor head injury. Lancet 2001;357:1391-6NoteNot applicable if: non-trauma case, GCS <13, age <16, warfarin or a bleeding disorder, obvious open skull fracture. Criteria checked against the rule card printed in Stiell IG et al. CMAJ 2010;182:1527-32.ReviewedFormula and thresholds checked against the source on 2026-09-28. If the source updates, this line will say so.
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